1. Field of the Invention
The present invention relates to an ink jet recording apparatus and an ink jet recording method.
2. Description of the Related Art
Ink jet recording apparatuses can produce recorded article at low cost and are more advantageous than electrophotographic recording apparatuses in power consumption, accordingly having come to be widely used. An ink jet recording apparatus records an image by ejecting an ink from a recording head. However, the ink can clog the ejection openings of the recording head or become thick in an ink flow channel due to the evaporation of the liquid component of the ink. This hinders proper ejection of the ink. When such an undesirable phenomenon occurs, the recording head is subjected to recovery operation for recovering the capability of properly ejecting the ink. This operation may be performed at regular intervals or before or after recording operation.
In general, such recovery operation is performed by preliminarily ejecting a portion of the ink, not intended to record an image, to a cap disposed at a position opposing the surface of the recording head provided with the ejection opening therein (ejection opening face). Alternatively, the ink may be forcibly discharged from the recording head by a negative pressure that is generated by the operation of a suction cap connected to a suction pump with the ejection opening face in contact with the suction cap. However, these recovery operations require a sucking member having a certain level of weight, such as such as the suction cap or the suction pump, and the sucking member needs a space for installation.
On the other hand, awareness of resource saving has risen recently, and accordingly downsizing and weight reduction are demanded of ink jet recording apparatuses. For a response to the demand, Japanese Patent Laid-Open Nos. 2003-231277 and 2004-114686 suggest approaches focusing on a member or a unit for collecting waste ink ejected from the ejection openings to recover the capability of the recording head, but not used for recording.
Ink jet recording allows recording on various types of recording media. In addition, for more satisfactory image recording, various types of ink have been devised according to the intended use, such as inks suitable to record photographic images on glossy paper or the like, or inks suitable to record a document on plain paper or the like. In recent years, ink jet recording has also been employed for recording business documentation including letters or characters, diagrams, and the like. Accordingly, the frequency of use of ink jet recording is increasing remarkably in business use. In business use, high optical density is demanded. From the viewpoint of increasing the optical density of recorded images, self-dispersible pigments are advantageously used as the coloring material of the ink.
Japanese Patent Laid-Open No. 2006-089735 and PCT Japanese Translation Patent Publication No. 2009-515007 disclose self-dispersible pigments developed for increasing the optical density of recorded images, focusing on the functional group to be bonded to the surfaces of the pigment particles.
On the other hand, the present inventors have found through their studies that if the suction member such as a suction cap or a suction pump is omitted from an ink jet recording apparatus for weight reduction and downsizing, the ink discharged for preliminary ejection is undesirably deposited on an ink receiving member. In particular, in the use of a phosphonate groups-containing self-dispersible pigment advantageous in increasing the optical density of recorded image as disclosed in Japanese Patent Laid-Open No. 2006-089735, the pigment particles are rapidly aggregated when the liquid component of the ink has evaporated. Thus, the ink is liable to be deposited like stalagmite on the bottom of the ink receiving member. If preliminary ejection is performed with the waste ink thus deposited, the stalagmite-like deposit of the waste ink is likely to come into contact with the recording head, thereby affecting the operation of the carriage or clogging the ejection openings. Although ink jet recording apparatuses provided with a member adapted to remove or flatten the deposit of the ink in the ink receiving member by scraping the deposit (scraping member) have been known, such a scraping member hinders weight reduction or downsizing.